A federal judge has rejected a lawsuit aimed at halting construction of SDG&E's Sunrise Powerlink through East County.

In a decision issued late Thursday, U.S. District Judge Roger T. Benitez refused to block the $1.9 billion transmission line, despite arguments that the federal government failed to fully assess the project's environmental impact.

He questioned the underpinnings of the suit, saying that those behind it had failed to follow through on a related legal appeal filed in 2009 with the U.S. Department of Interior.

That argument disappointed Powerlink opponents like Laura Cyphert, with the East County Community Action Coalition, one of the groups that pursued the suit. She and others believe Benitez sidestepped the environmental issues posed by the 117-mile project.

The court decision, Cyphert argued, "was really based more on a technicality than the merits of the case."

Jennifer Ramp, a spokeswoman for San Diego Gas & Electric, noted in an email on Friday that the validity of the project has been repeatedly upheld in court.

"With yesterday's decision, the Sunrise Powerlink has prevailed in every legal challenge that has been levied against it," Ramp wrote. "We expect that the few remaining legal challenges will be dealt with as well and work on the project will proceed on schedule."

The line will bring power to San Diego from Imperial County. Construction started last fall and is at least 15 percent complete.

Thursday's decision stemmed from a lawsuit filed by backcountry activist Donna Tisdale, the East County coalition, the Protect Our Communities Foundation and a group called Backcountry Against Dumps.

The suit argued that the U.S. Bureau of Land Management and the U.S. Fish and Wildlife Service failed to fully scrutinize the impact of the project on wildlife, wildfire prevention and related issues. The transmission route includes BLM land.

SDG&E officials say the project has been exhaustively studied and has passed muster with state and federal regulators.

Attorney Stephan Volker, who represents the project opponents, said he would appeal the Benitez decision.